* Update documentation
Describe how to improve Exception Decoder results.
Updated build option details.
* Added d-a-v's code. And updated description and debug macro.
* Update doc
Updated platform.txt - positioned -Os such that it can be overridden by `build.opt`.
Add suggestion of using `-Og` which may improve the Decoder's line number correlation
with the problem in the source code.
Untested adjustments to platformio-build.py
* Fixed code formatting
* Fixed example
Previously `-O3` in the example had no effect. It was overridden by later flags.
Reording the `-Os` allowed changing optimization to work. Somehow this triggered
a new warning "Stream.h:50:7: warning: 'f.Stream::_startMillis' may be used
uninitialized in this function". Replaced `-O3` with `-Og`.
* Proposed "Debug port" menu change
Preserves a pathway for `build.opt` override.
* Update boards.txt.py and docs - WIP
* Improve organization of optimization content.
Use "Debug Optimization" for menu name.
The menu item defines the initial optimization.
platform.txt - optimization parameter can be overridden by build.opt.
* Add fallback value for build.debug_optim to platform.txt
* update text and undo changes to platformio-build.py
* tweak text
* Added ':orphan:' mark to a06-global-build-options.rst
* Update doc. Added link in page index to 'Improving Exception Decoder Results'
* Update text to reference PR#8868 improvements for leaf function.
